This invention relates to the interconnection of devices on large scale chips, and in particular, it relates to the optical interconnection of devices on chips.
Integrated circuit chips are becoming larger and larger and the devices on them are decreasing in size thereby resulting in the creation of a problem as to how to interconnect devices at remote areas of the chip without incurring substantial delay in the transmission of information between these devices. One solution to this problem is to interconnect the devices optically. See, for example, the proposals presented in the article entitled "Optical Interconnections for VSLI Systems" by J. W. Goodman, et al., Proceedings of the IEEE, Vol. 72, No. 7, July, 1984, pps. 850-866. In FIG. 11 of the Goodman et al. article, the light emitted by a source on the surface of an integrated circuit chip is reflected by a hologram which is mounted a predetermined distance from the surface of the chip. A central problem with this approach is that the position of the beam directed back to the chip is critically dependent on the position of the external optical component. This is true not only of a vertical displacement of this component but also for lateral displacement of the component. For example, if the hologram is behaving like a curved mirror in reimaging the emitting device onto the detector, displacement of this hologram by a distance of .DELTA.x will cause the image to move by the distance of 2.DELTA.x. This sensitivity is a major disadvantage in such optical interconnecting schemes.